A standard motor-vehicle door latch has a rigid housing that is normally mounted on a door edge and in which are mounted locking elements including a pivotal lock fork that can engage around and retain a bolt or wedge carried on a door post and a retaining pawl that is also pivoted on the housing and that can retain or release the fork. In addition the housing contains an actuating and locking mechanism typically formed by various levers that are connected to inside and outside handles and inside and outside locking elements for operation of the retaining pawl in a manner well known in the art.
It is also standard to provide such a latch with a drive unit constituted by an electric motor and transmission that can move the elements of the latch between locked and unlocked positions, and even often into an antitheft position. In the locked and antitheft positions the outside door handle is decoupled from the latch mechanism. In the locked position the inside locking element is normally still operational, or the door can be unlocked by a double actuation of the inside handle. In the antitheft position the inside handle is deactivated so the only way to unlock the door is by use of a key.
Such a power-actuated latch also normally has various switches that are connected to the central locking system and to appropriate warning lights to inform the locking system and driver of the status of the lock, whether it is in the locked, unlocked, or antitheft position, and whether the door is fully latched or not. Hence it is standard to provide a plug on the side of the lock to which is connected one end of a multiconductor cable leading to the central lock system and dashboard and to the vehicle power supply. The plug has a plurality of terminals each connected to one end of an insulated wire whose other end is connected to a respective terminal on a switch, sensor, or motor.
This wiring is fairly difficult and, hence, expensive to install in the latch during its manufacture. It must be meticulously routed through the latch to keep out of the way of the various moving parts of the latch. Furthermore in use the latch is subjected to substantial dynamic forces. When the door is slammed, for instance, all the parts of the latch, including the wiring, are subjected to considerable stress. Simple vibration alone, which such a latch is also subjected to constantly during travel, can cause the wiring to work at its connections and eventually fail and come loose. A motor-vehicle door latch is known having a composite housing having walls forming a generally closed interior and formed of a plastic body forming at least one of the walls and a metallic reinforcing plate imbedded in the plastic body. Latch elements--normally a pivotal fork and retaining pawl--in the interior are pivoted on the reinforcing plate. Electrical circuit components having connection terminals are mounted on the housing in the interior and an assembly of contacts is mounted on the housing accessible from outside the housing. Respective conductors imbedded in the plastic body each have one end connected to a respective one of the contacts and an opposite end each provided with a respective connection formation joined to a respective one of the terminals.
Thus this system eliminates the use of free-running wires. The conductors are imbedded in the plastic body of the housing so that their paths and positions are perfectly controlled and stabilized. They therefore are not subject to damage in manufacture or use. Such conductors can easily be set with the metal plate in the mold used to make the housing so that they are fixed in place once the resin is injected into the mold and cured.
While this system is relatively effective, it could be better integrated with respect to the connections of the various parts and how the mechanical and electrical elements fit in the housing. In particular the conductors are imbedded in housing parts that are used for support of mechanical elements so that manufacture is difficult, especially when aiming at making the latch as compact as possible.